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Radio loses FM signal from time to time

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by JonnyCJ, Sep 30, 2019.

  1. JonnyCJ

    JonnyCJ Senior Member

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    Joined:
    Apr 13, 2010
    Location:
    Wirral
    Your Mercedes:
    ML350 Grand Edition 2011, ML350 Sport 2010, VW Splitscreen 1965
    As above and on all FM stations. Pretty sure it’s a dodgy aerial or connection, but would appreciate a heads up where to look first.

    Car is a 2010 ML350 with COMAND

    Cheers

    Jonny
     
  2. Botus

    Botus Senior Member

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    Joined:
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    Location:
    UK
    Your Mercedes:
    S500/2010/500
    a) antenna amps are known to go wrong
    b) FM radio was supposed to be dead in 2012, keeps getting a stay of execution but no one cares about the strength or signal quality these days
    c) 3 4 and 5g have stolen old analogue bandwidth and it isn't helping
     
  3. M80

    M80 Senior Member

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    Your Mercedes:
    Vito 115 Lwb Dualiner.
    If you have any USB devices plugged in to the 12 volt try unplugging them.
    They are known to create RF that can swamp the FM.
     
    JonnyCJ and Botus like this.
  4. OP
    JonnyCJ

    JonnyCJ Senior Member

    Messages:
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    Joined:
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    Your Mercedes:
    ML350 Grand Edition 2011, ML350 Sport 2010, VW Splitscreen 1965
    And indeed I do ! I have a bluetooth unit plugged into the Media Interface via USB, as well as a phone charger plugged into the 12v socket. Will see if they make a difference. Very helpful, thanks and saves pulling the car apart...
     
  5. M80

    M80 Senior Member

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    Your Mercedes:
    Vito 115 Lwb Dualiner.
    Some USB devices / chargers are better sheilded.
    When I propose to use one I tune to a weak station and power up the USB whatever, that way I can gauge any ill effect.

    I've 2 wireless chargers for our phones in the Vito. They are permanently powered independantly from Chinese 15watt USB supplies behind the dash.
    Both create a heartbeat type sound on FM but only when there is near no FM station signal. I'm happy enough with that.
    To prove all I need do is unplug 'em. The USB supplies have no effect.

    Oh! The Vito tuner amp is located above the rear view mirror, and the antenna hi along the top of the windscreen. Those mo mo's with the antenna into the rear screen likely wouldn't find USB gear sited at the front so critical.
     
  6. OP
    JonnyCJ

    JonnyCJ Senior Member

    Messages:
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    Your Mercedes:
    ML350 Grand Edition 2011, ML350 Sport 2010, VW Splitscreen 1965
    Sorted ! It was the 12v USB sockets.

    A very helpful post which I will pass on to all.

    Cheers

    Jonny
     
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  7. Botus

    Botus Senior Member

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    Your Mercedes:
    S500/2010/500
    good one from M80 (issue driven coz of nasty car phone / gadget chargers),
    I'd forgotten that, its the cause of many Vauxhall DAB drop outs too
     
  8. Colin Dunn

    Colin Dunn Member

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    Joined:
    Mar 6, 2018
    Your Mercedes:
    E220 BlueTec 2014
    I have no USB usage, but my 2014 EClass DAB keeps failing and the buffer wheel appears, as if the whole unit is restarting. Any clues anyone?
     
  9. Botus

    Botus Senior Member

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    Your Mercedes:
    S500/2010/500
    done that one to death

    if keen, see if there's a comand update it should help (main dealer or a few specialist garages). in 2016 the world moved forward and many an e class didn't cope with the additional channels that came in. If you live in the sticks and don't travel much many an owner never experience the issue and don't realise if the car could see more than 100 DAB channels it would keel over and die. They like to come here and argue that the update is unnecessary. The update fixes it so it can cope with seeing lots of channels without having a moment. It might also bring in some security fixes and general tidy up behind the scenes.

    The other idea is to check geographically where you experience issues what the expected signal and channel count looks like

    https://getdigitalradio.com/?slide=check-your-available-stations

    After that the Antenna amp isn't suitable for weak UK signals and can be swapped for a better one
     

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